Aqueous slurry explosive composition containing a chlorinated organic compound as sensitizer



12 Claims ABSTRACT OF THE DISCLOSURE In pourable aqueous slurry explosive compositions comprising an inorganic oxygen-supplying salt, water, thickener and fuel, the sensitivity of the composition is improved by additionally including in the mixture 21 chlorinated organic compound and a material which arrests the migration of any air or gas bubbles which have been introduced or occluded into the composition. In large diameter cartridges for unconfined detonation or in compositions for use in 4 inch or larger diameter boreholes, the gas bubble arrester may be omitted.

This invention relates to aqueous slurry explosive compositions and more particularly to aqueous slurry explosives which are sensitive to initiation in small diameter charges and yet are devoid of any self-explosive ingredient.

This application is a continuation-in-part of United States application Ser. No. 684,519, filed Nov. 20, 1967, now abandoned.

Explosive compositions consisting of an inorganic oxygen-supplying salt, such as ammonium nitrate, and a fuel ingredient, such as carbonaceous material or fuel oil, are now well known and widely used in blasting operations. Likewise, explosive compositions in a thickened aqueous slurry form consisting of an oxygen-supplying salt, water, a thickener and a sensitizing ingredient such as finely divided light metal are equally well known and widely used.

While an ammonium nitrate/fuel explosive is advantageously cheap to manufacture and simple to employ, it nevertheless possesses a number of shortcomings which prevent its wider application. For example, it has little or no resistance to the desensitizing effect of moisture attack in the borehole and therefore must normally be enclosed in waterproof packages. Because of the insensitivity of the ammonium nitrate ingredient, it must normally be employed in wide diameter charges and requires initiation by means of a substantial primer in order to ensure propagation. Additionally, because of a low bulk density in the borehole, the work done by the detonation of an ammonium nitrate/fuel explosive may be less than desired.

Similarly, while the use of an aqueous slurry explosive overcomes in some measure the problems of lack of resistance to water and the low bulk density encountered with the dry ammonium nitrate/ fuel explosive, this slurry explosive too requires substantial priming to ensure detonation and propagation and may normally only be employed in large diameter charges.

nited States Patent The sensitivity of both the aforementioned explosives may, if desired, be increased by adding thereto a selfexplosive ingredient such as for example, particulate TNT, PETN or smokeless powder. The addition of such self-explosive increases the ease with which a charge may be detonated and permits the use of the explosives in smaller diameter boreholes. The addition of such selfexplosives, however, adds to the cost of the compositions and increases the hazards involved in manufacture, transportation, storage and use.

It has been proposed by Royer et al. in US. Patent No. 3,184,351 (May 18, 1965) that the sensitivity of ammonium nitrate-fuel oil explosives may be increased by adding thereto a sensitizer mixture comprising a liquid chlorinated organic compound. The use of such a sensitizer in the amounts proposed may be demonstrated to be advantageous in increasing the ease with which the compositions may be detonated. However, the compositions of Royer et al. do not overcome the disadvantage of low bulk density in the borehole and lack of water resistance. In addition, the compositions carry with them a number of disadvantages which reduce their attractiveness for commercial use. These disadvantages include, for example, (a) a lack of flowability compared with ordinary ammonium nitrate/fuel oil explosives due to the stickiness of the mixtures resulting from the relatively large quantities of liquid chlorinated hydrocarbon required which, as may be expected, will cause borehole loading difficulties; (b) the volatility of the sensitizer mixture requires that the explosives be used nearly immediately after preparation since any delay will permit the sensitizer mixtures to evaporate reducing the sensitivity of the explosives; (c) the chemical reaction of the liquid sensitizer mixture upon the ammonium nitrate ingredient during the detonation of the explosives may produce noxious fumes of hydrogen chloride disagreeable to workers; (d) when employed with a pneumatic borehole loading apparatus, toxic fumes from the volatile sensitizer mixture will be created constituting a particular hazard in underground mines and resulting in considerable loss of the sensitizer mixture.

US. Patent No. 3,264,151 (Aug. 2, 1966) issued to -O. Osborn et a1. describes an explosive composition of high density and having a pliable, rubbery consistency, which composition comprises a mixture of alkali metal nitrate and ammonium nitrate dissolved in water, a relatively large quantity of halogenated hydrocarbon, a fuel, an additional oxygen-supplying salt and particulate aluminium. Such a composition, while utilizing the advantageous sensitizing properties of the halogenated hydrocarbons, fails to provide the pourability or pumpability required in an aqueous slurry explosive. Additionally, the composition of Osborn et al. is of very high density, generally in excess of 1.5 gm./cc., which high density may be attributed to the deaerating or deforming action of the halogenated hydrocarbon. Such a composition will normally increase in density on standing. In addition, if even larger quantities of halogenated hydrocarbon are employed in the composition of Osborn et al. in an effort to provide a pumpable slurry explosive, the ingredients of the composition will tend to segregate because of the incompatability of the halogenated hydrocarbon with the aqueous phase. Such segregation results in loss of sensitivity of the explosive composition.

It has now been found that the advantageous sensitizing property of chlorinated compounds may be utilized in a pourable or pumpable aqueous slurry explosive composition thus overcoming all of the aforementioned disadvantages.

It is, therefore, an object of the present invention to provide a pumpable aqueous slurry explosive composition which is devoid of any self-explosive and yet has improved sensitivity.

Another object of the invention is to provide an aqueous slurry explosive composition which may be detonated in small diameter charges.

A further object of the invention is to provide a sensitive aqueous slurry explosive composition which will not become insensitive during storage.

These and other objects of the invention will become apparent from a consideration of the following description and claims.

The improved slurry explosive composition of this invention comprises essentially at least one inorganic oxygen-supplying salt, water, a thickener, a fuel, a chlorinated organic compound and a material which aerates the explosive composition or which assists in arresting the migration of any minute bubbles of air which have been occluded during mechanical mixing of the ingredients. The presence of occluded gas usefully augments the sensitizing action of the chlorinated organic compound. Deliberate aeration of the composition may be accomplished, if desired, by the direct introduction of air or gas into the slurry as disclosed, for example, by J. D. Ferguson et al. in U.S. Patent No. 3,288,658 (Nov. 29, 1966). The combined effect of the presence of both the chlorinated organic compound and the gas bubbles on the sensitivity of the slurry explosive is substantially greater than the additive single effect of each of these when present separately particularly in small diameter charges.

In general, the chlorinated organic compounds suitable for use as sensitizers in the composition of the invention are aliphatic and alicyclic compounds wherein at least one carbon atom has attached thereto two or more chlorine atoms. These chlorinated organic compounds may be liquids or solids but are preferably liquids and include, for example, carbon tetrachloride, trichloroethylene, perchloroethylene, hexachloroethane, chloroform, perchloropropylene, hexachlorobutadiene, chloral hydrate, hexachlorocyclopentadiene, octachlorocyclopentene, and mixtures thereof.

Suitable material for arresting or stabilizing gas bubbles include, for example, the water soluble salts of lignosulphonic acid or the water soluble polyflavonoids such as, for example, .Rayfio-C, a trademarked product of Rayonier Inc., New York. These complex organic salts are unique in their air or gas bubble arresting or stabilizing properties. It is frequently possible to dispense with the use of an air bubble arrester when special means are employed to introduce air bubbles into the explosive composition. The use of air-carrying solids such as, for example, vermiculite or micro-balloons may not require the use of any special gas bubble arrester or stabilizer. However, where air has been occluded in the composition during mechanical mixing, or where gas has been injected or produced in situ by the reaction of gas-producing chemicals, the use of materials such as, for example, a water soluble polyflavonoid is essential when the explosive composition is prepared for use in small diameter charges.

The composition of the invention may also advantageously contain finely divided energetic light metal or metalloid, for example, aluminium, silicon, their mixtures and alloys, as an additional power ingredient. Typically up to 30% by weight of the composition may be aluminium or an alloy thereof. As previously mentioned, the addi tion of a chlorinated organic compound together with a gas bubble arrester or stabilizer to a thickened, pumpable, aqueous explosive slurry devoid of any self-explosive has the beneficial effect of substantially and unexpectedly increasing the sensitivity of the explosive composition.

It is therefore possible to utilize the sensitizing property of a chlorinated organic compound in an explosive composition without the limitations and disadvantages known heretofore. It is similarly now possible to prepare pourable or pumpable slurry explosive compositions devoid of self-explosives and yet which possess the sensitivity properties of self-explosive-containing slurries.

Preferred slurry explosive compositions of this invention contain from 50% to 88% by weight of at least one inorganic oxygen-supplying salt, from 4% to 20% by weight of water, from 1% to 20% by weight of a carbonaceous fuel, from 1% to 10% by weight of a chlorinated organic compound, from 0.3% to 10% by weight of a gas bubble stabilizer and from 0.2% to 5% by weight of a thickener.

A preferred inorganic oxygen-supplying salt for use in the explosive composition of this invention is ammonium nitrate. It may in some cases be advantageous to replace some or all of the ammonium nitrate by other metal nitrates such as sodium, potassium, barium and calcium nitrate. The particle size of the inorganic oxygen-supplying salt may be in the form of powder, granules or prills and part of the salts may be dissolved in the water ingredient.

The carbonaceous fuel ingredient is preferably an oleaginous hydrocarbon such as fuel oil or diesel oil. However, other carbonaceous material such as pulverized coal, starch, cellulosic materials, sugars, urea, formamide and partially nitrated hydrocarbons may be employed.

When employed, the aluminum or silicon or mixtures and alloys thereof must be in a finely divided form and may most suitably range from a fine dust to a grit size not greater than that passing through a size 6 Tyler mesh screen.

Preferred thickeners for use in the explosive composition are the gel-forming polysaccharides especially the mannogalactans such as guar gum or carab seed. Both ordinary and self-crosslinking mannogalactans may be employed.

It has previously been said that gas bubble stabilizers suitable for use in the composition of the invention include the water soluble lignosulphonates or the water soluble polyfiavonoids. While any water soluble salt of lignin sulphonic acid may be used, calcium, sodium and ammonium lignosulphonates are preferred. Suitable polyflavonoids are the polyphenolic extracts from wood or bark commercially available as the sodium salts and sold under the trademark Rayfio-C by Rayonier Inc., New York.

The preferred chlorinated organic compound suitable as a sensitizer is trichloroethylene.

The explosive composition may be prepared by processes well known in the art employing simple mixing procedures. Preferably the water is first added to the dry ingredients excepting the particulate ammonium nitrate and the optional finely divided energetic light metal or metalloid. The chlorinated organic compound and any oil soluble fuel employed are premixed together and incorporated into the aqueous phase and thereafter the particulate ammonium nitrate and optional particulate energetic light metal or metalloid are added, the whole being mixed to a desired final density. The explosive composition of the invention lends itself to preparation at the blasting site by means of the now well known slurry mix truck.

The following examples and tables illustrate the improved explosive composition of this invention but the latter is in no manner to be limited in scope to the embodiments described.

EXAMPLE 1 A slurry explosive composition containing as essential ingredients ammonium nitrate, water, and a fuel together with a thickener and a gas bubble stabilizer was prepared. To part of this composition was added a quantity of carbon tetrachloride. A 4 diameter cartridge of the composition devoid of carbon tetrachloride failed to be initiated by a gram pentolite primer. Using the same primer, a 4" diameter cartridge of the composition containing carbon tetrachloride was detonated completely. The results are summarized in Table I, the quantities shown being expressed as percent by weight of the total.

l Fired with 160 g. pentolite.

EXAMPLE 2 A slurry explosive composition containing as essential ingredients oxygen supplying salts, trichloroethylene, diesel oil, water, a thickener and stabilizers was prepared. A second similar composition was prepared except that the diesel oil was replaced with finely divided aluminium as a fuel. Both compositions were detonated without difficulty in small diameter charges. The results and properties are summarized in Table II, the quantities shown being expressed as percent by weight of the total.

TABLE II Mix No 1 2 Grained ammonium nitrate 35. 55 29. 05 Prilled ammonium nitrate 20. 20. 00 Grained sodium nitrate- 20.00 12.00 Trichloroethylene 8. 00 8. 00 Diesel oil 3.00 Aluminium (air at 15. 00 Guar thickenen O 0. 70 Water 12. 00 12. 00 Ammonium lignosulphonate stabilizer. 2. 50 3.00 Zinc chromate segregation inhibiter 0. 25 0. 25

100. 00 100. 00 Oxygen balance +3. 1 5. 9 Density, g./cc 1. 32 1. 34 Detonati 11 velocity (160 g. pentolite primer),

m./sec.:

2" diameter 3, 342

3 diameter 3, 577 Critical diameter (unconfined), inch 2. 5 1. 5 Critical diameter (confined), inch 1. 0 0. 5 Minimum primer (unconfined) l No. 8 caps. 2 3 No. 8 caps.

EXAMPLE 3 A slurry explosive composition was prepared comprising the following ingredients, the quantities being expressed as percent by weight of the total: grained ammonium nitrate 45.2% prilled ammonium nitrate 20.0%, grained sodium nitrate 12.3%, trichloroethylene 8.0%, diesel oil 3.0%, guar thickener 0.5%, water 8.0%, and ammonium lignosulphonate 3.0%. The composition was detonated in a 3 /2 inch cartridge at a detonation velocity (unconfined) of 2970 m./sec. using a 40 gram pentolite primer. The density of the composition was 1.25 g./cc. and had an oxygen balance of -3.2.

EXAMPLE 4 A slurry explosive composition was prepared comprising the following ingredients, the quantities being expressed as percent by weight of the total: grained ammonium nitrate 33.2%, prilled ammonium nitrate 20.0%, grained sodium nitrate 12.3%, trichloroethylene 8.0%, air-atomized aluminum 15.0%, guar thickener 0.5%, water 8.0% and ammonium lignosulphonate 3.0%. The composition was detonated in 2 inch diameter cartridges by means of a 120 g. pentolite primer and could be detonated bymeans of 3 No. 8 detonators. The unconfined velocity of detonation was 2370 m./sec. The composition had a density of 1.31 g./ cc. and an oxygen balance of --7 .3.

EXAMPLE 5 To demonstrate the sensitizing effect of the chlorinated hydrocarbons, two slurry explosive compositions were prepared similar to Mix No. 1, Table II, but devoid of any chlorinated hydrocarbon sensitizer. Neither composition could be detonated by means of a 160 g. pentolite primer. The properties and results are summarized in Table III, the quantities shown being expressed as percent by weight of the total.

TABLE III Mix N o Grained ammonium nitrate Prilled amonium nitrate Grained sodium nitrate Diesel oil- Guar thickener- Wate Ammonium lignosulphonate stabilizen Zinc ehromate segregation inhibiten.-- 2-ethyl-1-hexanol density controllen- Density, g./cc Detonation attempts at 4 diameter with 160 g.

pentolite primer 1 9/9 failed. 2 6/6 failed.

EXAMPLE 6 To demonstrate the sensitizing function of the gas bubble stabilizer, two slurry explosive compositions were prepared comprising ammonium nitrate, sodium nitrate, fuel, thickener, water and trichloroethylene but devoid of any bubble stabilizer. The compositions were packaged in 4 inch diameter cartridges and exposed to unconfined detonation by 160 g. pentolite primers. Neither composition could be detonated. The ingredients, properties and results are summarized in Table IV, the quantities shown being expressed as percent by weight of the total.

t 2/2 failed.

EXAMPLE 7 Two slurry explosive compositions were prepared containing as essential ingredients oxygen-supplying salts, water and a fuel together with a thickener and a gas bubble stabilizer. To one of these compositions, hexachloro 1,3-butadiene was added as a sensitizer. To the other, chloral hydrate was added as a sensitizer. Both compositions were detonated unconfined without difficulty in small diameter charges. The results and properties are summarized in Table V, the quantities shown being expressed as percent by weight of the total.

TABLE V Mix No 1 2 Grained ammonium nitrate 59. 4 29. 3 Prilled ammonium nitrate. 20. 0 Grained sodium nitrate 12. 0 Hexachloro 1,3-butadiene 8.0 Chloral hydrate. Aluminium (air a 9. 15.0 Guar thickener 0. 0.7 Water 8. 12.0 Zinc dust (segration inhibitor) 1.0 Ammonium lignosulphonate stabilizer. 3. 0 3 0 Glycol 0. 4

Density, g./cc 1. 4D 1. 29 Detonation velocity (160 g. pentolite primer):

2% in. diameter (unconfined) 1 3, 500 1 3, 740

2 in. diameter (unconfined) 1 3,

7 EXAMPLE 8 TABLE VI Ingredients:

Prilled ammonium nitrate Grained sodium nitrate Zinc nitrate (pH adjuster) Ammonium liguosulphonate stabilizen- Guar thickener (high viscosity grade) Potassium pyroantimonate (cross-linking agent QODNWONON Water Trichloroethylene. Fine silicon pow Density, g./cc 3 in. diameter cartridge (unconfined) primed with 20 g.

pentolite primer Fired When aqueous slurry explosives containing a chlorinated organic compound sensitizer are detonated in large diameter charges in the unconfined state, the aeration of the composition or the containment of any occluded air is not required in order to augment the sensitizing effect of the liquid chlorinated organic compound. By large diameter charges are meant explosive cartridges of about eight inches in diameter. In the unconfined state means a cartridge which is not placed in a borehole in rock or in a simulated borehole such as, for example, a steel pipe or the like. In the explosives art, the sensitivity of an unconfined eight inch cartridge is commonly regarded as being equivalent to the sensitivity of a cartridge of the same explosive at about four inches in diameter when said four inch cartridge is confined, for example, in a borehole in rock.

It has been found that a pourable or pmmpable aqueous, non'aerated slurry explosive composition devoid of any self explosive and containing as essential ingredients at least one inorganic oxygen-supplying salt, water, a thickener, a fuel and a chlorinated organic compound is sensitive to detonation in unconfined, eight inch or larger diameter cartridges. Occluded or introduced gas bubbles or a gas bubble arrester or stabilizer is not required as an essential ingredient so long as the charge or cartridge diameter is about eight inches or larger when detonated in the unconfined state.

The preferred slurry explosive composition for large diameter unconfined charges contain from about 50% to about 88% by weight of an inorganic oxygen-supplying salt, from about 4% to about 20% by weight of water, from about 1% to about 20% of a carbonaceous fuel, from about 1% to about 10% by weight of a chlorinated organic compound and from. about 0.2% to about 5% by weight of a thickener. Small quantities of other known ingredients such as, for example, segregation inhibitors, cross-linking agents and the like may also be usefully included in the composition.

The following example and table illustrate the explosive composition just above described but this aspect of the invention is in no manner to be limited in scope to the embodiment shown.

EXAMPLE 9 Three slurry explosive compositions containing as essential ingredients, oxygen-supplying salts (ammonium nitrate and sodium nitrate), water, a fuel, a thickener and trichloroethylene together with other, minor, nonessential ingredients were prepared in the following manner. The dry ingredients including the oxygen-supplying salts, the thickener and a dry fuel together with a crosslinking agent and a segregation inhibitor rwere blended together. To the blended dry ingredients were added a liquid fuel and trichloroethylene. Water was then added along with particulate aluminum when employed. The blended composition was packaged in 8 inch diameter thin wall polythene tubes, and initiated by means of a one pound pentolite primer. The results are summarized in Table VI, the quantities shown being expressed as percent by weight of the total.

TABLE VII Mix No 1 2 3 Prilled ammonium nitrate 49. 0 50. 55 54. 55 Sodium nitrate 12.0 t 0 0.2 0.2 8.0 8. 1. Water 12.0 12. Aluminum (air atomized)-.. 15.0 15.0 Detonation velocity 8" diameter (unconfined) (1 lb. pent olite primer) in mJsec 2,900 3,800 4,000 Density, g./cc 1. 50 1.47 1.44

As can be seen from the table, all of the test compositions were detonated unconfined at good velocity of detonation even in the absence of any significant amount of gas bubbles or the presence of any gas bubble stabilizer as indicated by the densities shown. It is expected from general experience in similar test procedures that these compositions would be detonatable in four inch diameter cartridges in the confined state.

What we claim is:

1. An aerated explosive composition comprising essentially at least one inorganic oxygen-supplying salt, water, a thickener, a carbonaceous fuel selected from the group consisting of oleaginous hydrocarbons, partially nitrated hydrocarbons, starch, cellulosic materials, sugars, urea, formamide, carbon and mixtures thereof, a gas bubble stabilizer selected from the group consisting of water soluble lignosulphonates, water soluble polyfiavonoids and mixtures thereof, and a chlorinated organic compound selected from chlorinated aliphatic and alicyclic compounds and mixtures thereof.

2. An explosive composition as claimed in claim 1 wherein the inorganic oxygen-supplying salt is selected from the group consisting of the nitrates of ammonia, sodium, potassium, barium, calcium and mixtures thereof.

3. An explosive composition as claimed in claim 1 wherein the chlorinated aliphatic organic compound is selected from the group consisting of carbon tetrachloride, trichloroethylene, perchloroethylene, hexachloroethane, chloroform, perchloropropylene, chloral hydrate and mixtures thereof.

4. An explosive composition as claimed in claim 1 wherein the chlorinated alicyclic organic compound is selected from the group consisting of hexachlorobutadiene, hexachlorocyclopentadiene, octachlorocyclopentene and mixtures thereof.

5. An explosive composition as claimed in claim 1 also containing an energetic metal or metalloid selected from the group consisting of finely divided aluminum, silicon and mixtures and alloys thereof.

6 An aerated explosive composition comprising essentially from about 50% to about 88% by weight of an inorganic oxygen-supplying salt, from about 4% to about 20% by weight of water, from about 1% to about 20% by weight of a carbonaceous fuel selected from the group consisting of oleaginous hydrocarbons, partially nitrated hydrocarbons, starch, cellulosic materials, sugars, urea, formamide, carbon and mixtures thereof, from about 1% to about 10% by weight of a chlorinated organic compound selected from chlorinated aliphatic and alicyclic compounds and mixtures thereof, from about 0.3% to about 10% by weight of a gas bubble stabilizer selected from the group consisting of water soluble lignosulpho- 9 nates, water soluble polyflavonoids and mixtures thereof, and from about 0.2% to about 5% by weight of a thickener.

7. An explosive composition as claimed in claim 6 also containing from to 30% by weight of an energetic metal or metalloid selected from the group consisting of finely divided aluminium, silicon and mixtures and alloys thereof.

8. An explosive composition detonatable in the unconfined state in at least eight inch diameter cartridges comprising essentially from about 50% to about 88% by weight of an inorganic oxygen-supplying salt, from about 4% to about 20% by weight of water, from about 1% to about 20% by weight of a carbonaceous fuel selected from the group consisting of oleaginous hydrocarbons, partially nitrated hydrocarbons, starch, cellulosic materials, sugars, urea, formamide, carbonand mixtures thereof, from about 1% to about 10% by weight of a chlorinated organic compound selected from the group consisting of chlorinated aliphatic and alicyclic compounds and mixtures thereof and from about 0.2% to about 5% by weight of a thickener.

9. An explosive composition as claimed in claim 8 wherein the inorganic oxygen-supplying salt is selected from the group consisting of the nitrates of ammonia, sodium, potassium, barium, calcium and mixtures thereof.

10. An explosive composition as claimed in claim 8 wherein the chlorinated aliphatic organic compound is selected from the group consisting of carbon tetrachloride, trichloroethylene, perchloroethylene, hexachloroethane, chloroform, perchloropropylene, chloral hydrate and mixtures thereof.

References Cited UNITED STATES PATENTS 3,184,351 5/1965 Royer et al 149-46 X 3,255,058 6/1966 Wyman et al. 149-87 X 3,264,151 8/1966 Osborn et al. 149-46 X 3,369,945 2/ 1968 Craig et al. 149-44 X 3,382,117 5/1968 Cook 14944 X 3,390,028 6/1968 Fee et al. 149-44 X 3,390,030 6/1968 Fee et al. 149-44 X 3,390,032 6/1968 Albert 149-44 X 3,397,096 8/ 1968 Falconer et al. 149-44 X 3,400,026 9/1968 Fearnow 149-44 X CARL D. QUARFORTH, Primary Examiner.

S. J. LECHERT, Assistant Examiner.

US. \Cl. X.R. 

